Rama observed there was a fire caused due to spilling of kerosene oil from kerosene lamp in her area. People of her surroundings wanted to douse off fire using water. She stopped them from doing so instead advised them to throw sand on fire. They managed to extinguish fire using sand.
Why do you think Rama stopped people from using water to extinguish fire?

Explanation

Since kerosene is lighter than water. So, water cannot be used to put off fire involving oil as it will sink below the oil and oil will keep burning on the top.